On 16/03/2016 04:55, Xiao Guangrong wrote: >>>>> >>>>> Probably not. AFAICT KVM does not rely on it being loaded outside that >>>>> region. xsetbv isn't insanely expensive, is it? Maybe to minimize the >>>>> time spent with interrupts disabled it was put outside. >>>>> >>>>> I do like that your solution would be contained to KVM. >>>> >>>> I agree with Andy. We do want a fix for recent kernels because of the >>>> !eager_fpu case that Guangrong mentioned. > > Relying on interrupt is not easy as XCR0 can not be automatically > saved/loaded by VMCS... Once interrupt happens, it will use guest's XCR0 > anyway.
Right, that's why an xsetbv while interrupts are disabled is appealing. Paolo
